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Discussion Starter · #1 ·
Apologies for posting out of forum but Ninja 650R owners tend to be newbies and this forum has some grizzled veterans. I did have an EX500 a few years back.

Here's the latest foulup working on my '07 Ninja 650R. I brain cramped and snapped off a bolt securing the head to the lower half. The broken bolt is one of two located next to the camchain but on the outside of the head. The book calls for 12nm torque and the bolt snapped somewhere around 20 - 22nm. The remains of the bolt are securing head to block. In other words, if the broken bolt were properly torqued I wouldn't need or want to do anything. The head is secured internally by 6 well spaced 10mm bolts torqued to 36 foot pounds (used bolts) and 40 for new. I'm willing to entertain crazy thoughts and ideas on this one. As I see it my options are:

1. With difficulty, drill out the broken bolt. That may not even be possible because of the location, needing an extender, not being able to use an EZ out, etc. The operation would probably chew up the threads so I'd need to rig a nut and bolt replacement.

2. Leave the bolt in and don't worry about it as opposed to worrying the overtorqued area will or already has warped the head.

3. Use the thinnest cutting tool available to go in sideways and cut the bolt. That will chew up part of the aluminum on the outside but would allow me to pull the head and drill out the remnants.



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· Tanker Clown
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If you were to some how find an extended length left hand twist drill bit, I’d be willing to bet removal would take you around 10 seconds.

As there is no load on the bolt now that the head is snapped off, once the drill bit caught it would spin the remnant right out.

Aside from that, a drill guide would be a really good idea to ensure the bit is centered. Good luck.
 

· Moderating: Fair & Just
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Apologies for posting out of forum but Ninja 650R owners tend to be newbies and this forum has some grizzled veterans. I did have an EX500 a few years back.
No apologies needed. Love having you here. Everyone's more than happy to help. Hope to see you around even after your 650 is up and running. ;)
 

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if the head is snapped of that allen bolt it means the thread is there just under the flange so remove all the other bolts remove the head and grab the remaining portion with some grips and remove. then find a replacement and re set the head only this time to the correct torque.
 

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I would go with a drill guide and reverse drill bit if that was all you were trying to accomplish. One thing I would also look at if I understand correctly you were reassembling this unit and over torqued it. You may have warped other aspects of the head and/or the gasket. Taking apart and starting over and double checking everything may not be a bad idea to insure it is correct and undamaged. It may not be anything just a thought. I know this type of thing is enough to make me throw a few words out, that are unpleasant loudly. Good luck with it.
 

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yes well put. was thinking along the same lines as myself why risk it.
did a similar thing on the scooter engine head bolts 30lbs/ft side bolt 10lbs /ft forgot to change the torque and snapped the bolt. after stripping the head back there was enough of the bolt showing to get some grips on it and screw it out. no other damage in the end so just replaced the bolt on reassembly.
 

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Discussion Starter · #7 ·
I thank you all for the replies and ideas. I spoke with a friend and engineer today and feel much better. Here's my takeaway from that converstation:

1. The purpose of torqueing the bolt is to prevent it from coming loose.
2. The bolt's purpose is to keep the head/block gap constant.
3. Extra torque pressure does not close the head/block gap but is absorbed by the bolt.
4. When the bolt head snaps off pressure is relieved and theoretically the bolt is free spinning.
5. As long as the bolt is threaded to block and head, proper gap is maintained.
6. The engineer's thinking crystallized when I told him this bolt is tightened last in the sequence and after all the bolts located under the valve cover. It's a "feel good" bolt and essentially not necessary.
6. The bottom line is that nothing need be done other than maybe silicone the bolt to keep it from moving.
 
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